Brainstorming how to keep water costs low

[Aisha M.]

I have a duplex where the water is not separate. The tenant uses too much water via (doing laundry every single day) and doesn't want to foot the costs. Aside from many issues, I decided i'm not renewing her lease next year since she's proven to be dishonest about many things. 

What are some ideas (legal) to control this OR avoid this overuse on utilities going forward?